1. Technical Field
The present invention relates to a projector that projects an image formed by a liquid crystal panel or any other suitable light modulator on a screen.
2. Related Art
There is, for example, a projector including a zoom lens as a projection system and a light source lamp whose luminance is adjusted in accordance with the focal length of the zoom lens (see JP-A-2003-131323). Any change in brightness of the projection image can thus be suppressed even when the size of the image is changed.
In the projector described in JP-A-2003-131323, however, since the brightness is adjusted by changing the output from the light source lamp, light is likely blocked in a projection system in an unintended manner, for example, by a lens barrel or a diaphragm when the zoom position of the zoom lens is set in a telescopic position. The light blockage may cause the projection system to be heated, disadvantageously often resulting in focus shift of the projection system. Further, when the luminance of the light source lamp is adjusted, the changeable amount of light is small and hence a stable amount of light is unlikely obtained.